How can you rewrite this

Rewrite in Trigonometric form: 16-4i

Thanks in advanced!

z = 16 - 4i
z = r[cos a+i*sin a]
r^2 = 16^2+16 = 272
r = 4sqrt17
a = tan^-1 (-4/16) = -14 degrees = 346
z = 4sqrt(17)[cos (346) + i*sin(346)]
Answer c is correct

z = |z|(cosΘ + isinΘ)
|z| = √(16²+4²) = √272 = 4√17
tanΘ = (-4/16)
Θ = 6.038 radians

z = 16-4i = 4√17(cos 6.038 + i sin 6.038)

4i-16

16-4i
=16-sqrt(-16)
good luck !